Method of burning liquid fuel



E. v. MICHAUD I I METHOD OF BURNING LIQUID FUEL Filed Feb. 15. 1942 4 Sheets-Sheet 1 FlZe'ar VM Q I I 2% July 10, 1945. v, MICHAUD 2,379,979 v METHOD OF BURNING LIQUID FUEL Filed Feb. 16, 1942 '4 Sheets-Sheet 2 -1NVENTOR2 Flzear V/Y/Zc/m July 1945- E. v. MIcHAUb 2,379,979

METHOD OF BURNING LIQUID FUEL Filed Feb. 16, 1942 4 Sheets-Sheet 5 'I I I I I I I I I I 5 I INVENTOR. flzeczr 1/ Wwhauci,

E U F D T. U Q I. G N I R U B F O D O m E M E, v. MICHAUD July 10', 1945.

Filed Feb.. ie'sj1942 4 Sheets-Sheet 4 Patented July 10,1945

2,379,919 METHOD or BURNING LIQUID FUEL Elzear V. Michaud, Chicago, 111., assignor to Harold T. Ames, Wilmette, Ill.

' Application February 16, 1942, Serial No. 431,122

6 Claims. (01. 158-1175) This invention relates to a method of and means for burning liquid fuels, particularly the heavier hydro-carbons, commonly known as furnace oils, and has for its principal object the provision of a new and improved burner of this type.

It is a main object of the invention to provide a method of preparing liquid fuel for combustion in several distinct steps, the first step vaporizing the fuel under pressure and the subsequent steps including expanding of a portion of this vapor and mixing it with pre-hea-ted air to gasify the vapor prior to its passage into a zone of combustion.

It is a further'object of the invention to provide an apparatus for burning liquid fuels wherein vaporizationof the fuel is accomplished at temperatures below the coking temperature of the fuel and wherein thefuel is kept in a turbulent or activatedcondition by recirculation of a the pre-heated-air and coking of the apparatus is prevented.

Still further objects of the invention, not spepart of the'vapor, the remainder of the vapor ciflcally mentioned here, will be apparent from the detailed description which follows, referencebeing had to 'the'accompanying drawings in which a preferred embodiment of the invention is shown by way of example and in which: 7 Figure 1 is a side elevational view of a preferred embodiment of the invention;

Figure 2 is an end elevational view taken substantially along the line 22 of Figure 1, looking in the direction ofthe arrows;

Figure 3 is a cross-sectionakview along the line 33 of Figure 1, looking in the direction of the arrows;

Figure 4 is a cross-sectional view through the median longitudinal line of the burner and taken substantially along the line 4-4 of Figure 2, looking in the direction of the arrows;

Figure 5 is a cross-sectional view through .the needle valve structure;

Figure6 is a cross-sectional check valve structure; and I Figure 7.is-a diagrammatic view illustrating the principle of operation of the burner.

In the prior art, of which I am aware, burners for the consumption of liquid fuel, such as keroview through the ible conduit, usuallya rubber hose, to a tank in which fuel is maintained under pressure. In devices of this kind, fuel from the tank is passed through a throttling valve located at the junction of the flexible conduit and the burner and passes through that valve into a vaporizing unit, usually comprising a coil of pipe. The outlet end of the vaporizing unit connects to a nozzle which is located in such a manner that the vapors discharged from the nozzle pass axially through the coil-like vaporizing unit to heat the same. A suitable housing encases the vaporizing unit and serves as a protection'for the same.

In devices of this kind in operation the throttling valve is set to permit a limited amount of fuel to pass into the vaporizing unit to be vaporized therein and to pass therefrom for burning. Because of the limited amount of fuel in the vaporizing unit, this unit is operated at a relatively high temperature, usually high enough to heat the unit to a light cherry-red color. This temperature being above the coking point of the fuel causes the vaporizing unit to become plugged, with hard coke which can be removed only by heating the unit exteriorly and passing compressed air or oxygen through it to burn out this deposit.

The present invention employs a different method. Fuel is supplied to the vaporizing unit 7 under full pressure through conduits of crosssectional area large enough to supply fuel to the unit at a higher rate than is required. Suflicient. liquid is maintained in the vaporizing unit to absorb enough heat to keep the temperature of the unit below the coking point of the fuel.

In a portable burner embodying this method of operation, the flexibleconduit fromthe source of fuel is extended through a valve as before for safety reasons and the fuel passes into a vaporizing unit which contains a larger area of heating surface than has been used heretofore for a burner of equal capacity. The outlet end of this vaporizing unit is connected through a needle valvestructure to an orifice through which vapors are discharged to pass axially through the vaporizing unit, as before.

The valve at the inlet end of the vaporizing unit is not the throttle valve by which the consumption of the fuel is regulated but rather, in

operation, this valve is run wide-open and the ducts through it are large enough so that the flow of fuel into the vaporizing unit is the same sene andthe lighterhydro-carbons or so-called I furnace ,oils. have been constructed as portable as if the valv'e were not present. With this arrangem'ent, the vaporizing unit is maintained relatively full of liquid fuel which is heated therein-sufllciently'to vaporize the fuel and because of the-'highabsorption of heat to provide for the latent heatof vaporization of fuel, the Y temperature of the vaporizing unit is maintained-- mation of coke therein and any non-vaporizable Owing to this larger area of heating surface to which the fuel is exposed, fuel may be vaporized to produce an excess of vapor and the orifice through which the vapor is emitted is calibrated to produce the desired consumption of fuel in gallons per hour for the particular unit. This excess vapor is returned through a suitable conduit into the inlet conduit of the vaporizing unit where itmixes with the liquid fuel to agitate the same and maintain it in a turbulent condition within the vaporizing unit. This produces a recirculatory effect and will be recognized as an adaptation of my prior Patent No. 2,120,257, is-

sued June 14, 1938. Since the vapor so mixed with. the fuel is at a higher temperature than the fuel, the fuel-will be preheated prior to passing into the vaporizing unit and some. of the vapor may be condensed back into liquid.

In the burners of the prior art, the vapor discharged from the nozzle is burned in close proximity to the vaporizing unit and nozzle, air of combustion being'drawn directly from the immediate surroundings, The method of the present invention difiers from'the prior art in that the vapors discharged from the nozzle are expanded and simultaneously heated to gasify them prior to burning. In a burner embodying this method, the p rizing unit is surrounded by a housing that is arranged to entrap a portion of the com-' bustible mixtures discharged from the nozzle and to burn that mixture in contact with the vapori ing unit to provide heat therefor. This mixture is burned in the presence of air drawn into 'the housing through perforations therein; these perforations'being' of such-area as to insure an ample supply of air. The mixture of burned gases and air is drawn around the vaporizing unit and into contact with the vapor stream. Fresh air may be drawn into the housing through auxiliary openings and mixed with this mixture of burned gas and air to insure suflicient air for combusg tion, these auxiliary openings having suitable control means so that the amount of air so admitted may be controlled. .The mixture is heated to a temperature above the gasification temperature of the vapor so that through its intermingling with the vapor, the vapor becomes gasified prior to its passing into the cone of combustion and through that cone into the zone of combustion outside of the burner. Thus it will i be seen that the housing not only serves as aprotection for the vaporizing unit but also serves as a mixing chamber in which the fuel is prepared for burning.

.As is well understood by-those skilled in the art, kerosene and furnace oils, commonly known as distillates, are available in various grades designated by numbers 1, 2 and 3, and will be vaporized to the end point at temperatures of approximately 600 Fahrenheit. As is also well un-f derstood by those skilled in the art, such fuels if heated to a temperature of about 750 Fahrenheit will be vaporized so rapidly that theheavier the teachings of the present invention, thearea portion of the fuel or foreign particles in the fuel will be kept in suspension and swept out of the vaporizing unit with the vapor.

Inasmuch as some of these particles may be too large to successfully pass through the nozzle through which the vapor is allowed to escape from the system, in the preferred embodiment of the present'invention, a chamber is provided immediately adjacent the nozzle. Vapor passing into this chamber passes from a small diameter conduit into a larger space and its velocity is decreased and solid particles carried in suspension in the vapor gravitate out and are collected at the bottom of the chamber.

In the preferred embodiment of my invention, a tap leads out of the bottom part of the chamber to permit periodic flushing out of the chamber, thereby to convey these non-combustible particles out of the burner.

In the starting of burners of this type, liquid fuel is usually drawn through the burner into the housing and ignited and burned to preheat the burner to operating temperature. The tap leading out of the sediment chamber adjacent the nozzle may be utilized to draw this fuel into the housing, carrying with it whatever sediment 'is in the chamber, with the result that'the bumthat pressure'indicated by a suitable gauge 3. An outlet 4 is equipped with a valve which may be closed to seal the fuel in'the tank under pressure.' Connected to the outlet E is a conduit 5 which in a portable unit is flexible and. usually a high pressure hose. Connectedto the opposite end of the conduit 5 is a strainer valve 6 in which the fuel is strained to remove from it larger particles that may be contained in it. This portion of 'the equipment forms no part of the present invention and is all old in the prior art, there being several sources of supply through which these'devices may be obtained.

The burner shown to illustrateth'e invention is seen best in Figures 1 and 2 and consists of an inlet conduit 1 connected to the source. of fuel through valves and leading through conduit 8 into the inner layer of the two layer helical coil able means may be'used within the teachings of the invention.

Conduit It leads through a suitable T-connection ll into two paths, the one extending through a pipe l2 to the needle valve chamber l3 and the other through a pipe 14 and a check valve l5 anda pipe Hi to 'a T-connection I1 located between the inlet conduits I and 8.

Surrounding the vaporizing unit 9 isa housing 20 which has an outlet orifice 2| and an inlet orifice 22, these orifices being preferably round and located with their centers on the axis of the gen erally cylindrical vaporizing unit 9. The housing contains suitable means for spacing the vaporizing unit in this position, this means in the drawing being shown as supporting members 23, there being four of these members shown; however, the number, size and location of the sup porting members may be varied within the teachings of the invention.

Surrounding the inlet perforation '22 in the I housing 20 is an air cone 24 formed as a cup-like member having a perforated bottomthrough the central perforation 25 of which the nozzle 26 is projected so that vapor discharged from this nozzle will enter the housing centrally of the vapor.- izing unit 9. The air cone 24 is also provided with (other. openings 21 through which air may be drawn. by the aspirator effect of the vapor discharged from the nozzle, and a shutter 28 may be provided to permit regulating the amount of airso admitted to tho housing with the vapor.

The front end wall of the housing 20 is provided with a perforation 2| centered upon the axis of the vaporizing unit 9. Inthe embodiment shown in the drawings, the wall around the periphery or this perforation is turned inwardly of the housing forming a scoop for directing a portion of the 'vapor into the housing. It will be apparent that the quantity of vapor so directed is El. and the distance between the end walls of the housing and the end of the coil 9. In the drawings, the diameter of the opening 2i is shown as less than the diameter of the coil 9, this showing being by way of example as I contemplate varying this particular dimension within the teachings of the invention. Located near the bottom of the housing and upon opposite sides of the vaporizing unit are a plurality of perforations 29 through which air is drawn into the housing as will presently appear.- As shown,

these openings are in two rows evenly spaced" from end to end of the housing. Other arrangements of the openings are contemplated including bunching the same near the outlet end of the housing. The combined area of the plurality of openings must be maintained large enough to permit free passage of the required amount of air into the housing and the number and pattern of openings employed for this purpose is not of primary importance.

As will be seen best in Figure 5, the. nozzle chamber indicated generally at E3 is defined by a central member 30 which resembles the cross over T fitting commonly used in pipe connections. Pipe it leads into th'e "member 36 and nozzle 2t leads out of the member, being located in an opening disposed 90 from the opening into which pipe i2 is fitted. Opposite the nozzle 25 is a needle valve assembly comprising a main body portion 3:, that is threaded into the member so and through which a valve stem 32 is extended,

the body 3i being threaded to co-operate with threads on the valve stem. Locatedwithin the body at and surrounding the valve stem is a chamber 33 of diameter larger than valve stem controlled by the diameter of the opening :2 which chamber is sues with a. packing material 34 that is maintained under compression and in engagement with the valve stem by a suitable packing gland 35. The valve stem. 32 carries a tapered shoulder 36 which may be brought to bear against a tapered seat in the nozzle structure 31 to close the nozzle. Preferably a pin 31 projects from the valve stem concentrically of the seat 36 and extends through the orifice in the nozzle 26, this pin being smaller than the orifice and serving to free the orifice of the foreign material when the valve is closed.

- Valve stem 32 is provided with a suitable collar 38 and when the stem is rotated by suitable means, such as the handle 39 to back the shoulder 36 away from the seat, to open the valve, the collar 38 will be brought into engagement with the end of the main body member 3| to prevent further opening of'the valve. This eliminates the possibility of the valve being open too far and if collar 38 is properly positioned on the stem.

the valve will be fully opened when this collar engages the member 3 I,

Leading out of the bottom of the member 30 is a conduit 40 which connects through a suitable valve 4| (Figs. 2 and 4) to a conduit 42 leading into the housing 20 near the bottom thereof. With the needle valve closed through the engagement of the shoulder 36 with the seat-in the nozzle structure and the valve 4| open, liquid in the chamber will pass out through the bottom thereof carrying with it any solids that, may be col lected, those' solids passing with the liquid through the pipe 42 into the housing where they may be burned or otherwise removed from the burner.

The particular needle valve structure just described may be varied or other types of valves may be used within the teachings of the invention; however, the structure shown is an advantageous one. The member 31 and stem carried thereby, and the nozzle 26 can be unscrewed from member so. This renders the chamberreadily acces'sible for inspection and cleaning and the stem and nozzle may also be readily inspected and cleaned while removed from the remainder of the valve. The thread 32 forms in eiiect a labyrinth provided with a check valve!!! arranged to permil: the flow of vapor as above and to prevent the now of fuel in 'a reverse direction.

Pipe M leading into the check valve l5 leads into a, chamber t5 which is closed by a ball t6 that rests upon a seat and is maintained thereon by a spring t'l compressed under the action of a suitable adjusting stud 48 threaded into the valve housing.- Conduit l5 leading out of the valve communicates with a chamber 49 located above the ball so and around the ball so that when the pressure in the chamber 45 exceeds the combined pressure of the Iuelin chamber 49 and the tension of spring 51, the ball will be moved upwardly ofi of its seat. to permit the vapor to pass from chamber as into chamber 49 and thence into the fuel stream.- When the valve is of! of its seat, suit- 7 The chamber in member so is.

' able guide prongs 49' maintain it in alignment with the seat so that whenthe pressure in the two chambers is-equalized, the valve will be reseated by the pressure of the spring. Should the pressure in chamber 45 fall below the pressure in chamber 49, the valve 46 prevents flow of fuel into chamber 45. It is noted that this valve is chamber it, I do not wish'tobe limited to this particular structure as other structures may equally well be'used for this purpose within the teachings of the invention.

The burner thus described is operated in the following manner:

Fuel is placed in the tank 5, this fuel being either kerosene or furnace'oils such as the furnace oils now known as numbers 1, 2 and 3, the burner thus described having been successfully operated with fuels of this range. The pump is operated to'build up on the fuel a working pressure preferably between 35 and 45 pounds, although if desired lower pressures may be used. Pressures above 45 pounds are not necessary. Valve t is opened and valve 6 is opened and the blow-off valve at is opened to drain into the bot-- noticeable and the vapor discharged from the nozzle flows in an apparently steady stream. The

rapid surging keeps the fuel in the vaporizing unit in an agitated condition.

As will be seen in Figure 7, the vapor 50 dis- -charged from the nozzle flows axiallythrough the generally cylindrical space formed by the inner layer of coils of the vaporizin unit 9, expanding as it moves away from the nozzle. The velocity and rate of expansion of the vapor stream are relatively high and fill the space within the unit a to overflowin particularly so near tom of the housing 28 a quantity of fuel. The

lower ones of the two rows of openings 29 are located above the bottom of the housing a distance equal to the depth of the fuel required to properly start the burner. Excess fuel will escape from the housing through these openings. Valve M is then closed as is the valve 6 and the fuel ignited, a piece of paper or waste may be inserted in the housingthrough opening it to aid in igniting the fuel if desired. The liquid fuel in the vaporizing unit a will tend to expand due to the application of heat to it but will be prevented from expanding by being confined in a closed chamber As soon as the fuel in the bottom of the housing is burning freely, the needle valve is operated to back the shoulder 36 away from the seat in the nozzle slightly so that the A fuel may expand and a small quantity of the liquid may be discharged into the housing, this additional fuel burning to hasten the heating of the torch. As the burner becomes hotter and the liquid in the vaporizing unit 9 approaches the vaporizing temperature; the needle valve is opened gradually and when nothing but vapor is discharged from the nozzle, fuel valve 6 is cracked slightly to apply pressure to the small quantity of fuel still remaining in the vaporizing unit. This application .of pressure intensifies the fire burning in the housing and hastens the vaporization of the fuel, yalve 6 being opened gradually until it is fully open and full pressure is on the fuel in-the vaporizing unit. In this manner, the

. burner is soon brought up to operating temperature and is capable of discharging a stream of vapor out of the nozzle with the'needle valve wide open and with the fuel inlet valve 6 also wide open.

As soon as the burner has come up to operating temperature, more vapor will be can be discharged through the nozzle and the excess will flow through the check valve l5 into the stream of fuel entering the vaporizing unit. For a few-minutes the action of the check valve the end of this unit farthestfrom the nozzle 26. The area of the opening 2i is not large enough to permit all of the vapor to pass through it and as a result, some of the vapor is deflected off of the outer edges of the stream and directed into the box-like chamber within the housing 20 as indicated by the .arrows 5i in Figure 7. Air is drawn into the housing through openings 29 as indicated by the arrows 52 and mixed with the vapor to burn the same in the space around the vaporizing unit 9, the combined areas of the openings 29 being sufliciently great to insure that more air will be drawn into the housing than will be required to completely burn the vapor therein This mixture of burned gases and air is at a temperature of approximately 1600 Fahrenheit and passes around the end of the vaporizing unit adjacent the nozzle 26 as indicated by the arrows 53 and mixes with the vapor 50 as that vapor is expanding in its travel from the nozzle. The vapor coming out of the nozzle being at a temperature below 750 F. is clearly visible having a whitish fog=like appearance. mixes with it, the vapor becomes invisible and there isa zone, indicated at 5 8, in the central portion of the cylindrical like passage through the vaporizing unit in which the mixture of vapor and pre-heated air becomes invisible, indicating a gasification of the vapor. When this condition is reached, gas flows as explained above and indicated by arrows 5i and is burned as was the vapor during the warm-up period.

As will be well understood by those skilled in .the art, petroleum vapors become completely v in Figure and the. violet color at 5 6. With generated than '70 will be slow and a violent surging will be notice- 78 the fuel pressure at approximately 40 pounds, this cone is clearly visible, extending several inches beyond the orifice 2| leading out of the housing. Beyond the cone in the zone of secondary combustion, the flames indicated at 51 in Figure 7 are a very light, almost invisible, color when in open air and when the flames are directed into a suitable combustion chamber become clearly invisible, denoting high perfection in combustion.

The rapid expansion of the gas flowing out of the housing which from the foregoing descrip- As the hot air.

tion will be readily recognized as a mixing chamber, provides a partial vacuum for drawing air into the openings 29 in this chamber. Th aspirating effect of the rapidly moving, vapor is not relied upon solely to draw air into the housing; in fact, the operation of the burner is improved when the openings 21 in the air cone are closed and all of the 'air ultimately brought into contact with the vapor stream is preheated prior to its mixing therewith.

With kerosene as a fuel and 40 pounds of pressure used, a very hot flame is obtained, this flame being approximately 2500 F. at a point just beyond the tip of the cone 56. This, as will be recognized by those skilled in the art, is a temperature approximately 500 F. higher than the temperatures that can be obtained in the burners of this class now available and using kerosene as a fuel.

I "With No, 3 furnace-oil as a fuel, slightly higher temperatures inay be obtained. Even with these highertemperatures, the vaporizing unit remains black after hours of steady operation,

' indicating that the temperature of this unit is not above 750 F. and after hours of operation the vapor 5|] discharged from the nozzle remains visible as a fog-like vapor indicating a temperature not above 750 F. and the burner may be operated for a long period of time without danger of forming a hard coke-like deposit within the vaporizing unit.

Any impurities in the fuel or unvaporlzed portions thereof will be carried with the vapor out of the unit 9 through conduit In by the relatively high velocity of this vapor. When the vapor enters the chamber in member 30 its velocity will be reduced and any particles suspended in the vapor will be droppecl, falling to the bottom of the chamber to be washed out when valve ll is opened to start the burner. If desired, valve 4| may be opened for a short time lowed to burn itself out until the burner loses so much pressure that it starts to smoke at which time the needle valve may be closed and the small amount of vapor remaining in the conduits allowed to condense therein.

From the foregoing, it will be apparent that the present invention is not limited to a burner of the portable type shown by way of example asphalts and materials of that type which'may when the burner is running. This will cause an increase in the velocity of vapor and fuel in the vaporizing unit, cleaning the same of sludge that may be collecting and also cleaning /the chamber. The vapor and sludge thus discharged enters the housing where it burns, leaving any non-combustible portion of the sludge in the bottom of the housing. 4 I r While preferably valve 4| is opened only during brief intervals while the burner is in operation to blow down theburner, if desired it may be opened, partially at least, and left open for a longer period. The vapor discharged through the valve 4| and burned or partially burned in the housing reduces the temperature of the flame 51 and at the same time increases its size. The added fire in the housing increases the amount of vaporizing capacity of the unit 9, permitting producing the lower temperature large volume flame for a considerable period of time.- Although the temperature of the flame is lowered, combustion is not impaired and under circumavailable, practically perfect combustion results. The burner may be run with vapor feeding through valve 4| until combustion is impaired, at which time valve 4| is closed, and the only vapor allowed to escape is that passing through nozzle 26. The burner will soon return to normal conditions, after which the check valve- IE will function as before. 1

' Wheifit isidesired to shut down the burner, oil supply valve 6 is closed and the fuel in the be melted in stationary equipment as contrasted from the portable equipment shown in the drawings.

The burner of the present invention is pos-' sessed of many advantages by reason of the method employed in burning the fuel, the fuel being first vaporized at a temperature low enough to minimize the precipitation of coke out of the liquid fuel, with the fuel maintained in turbulent conditi'on during vaporization preventing coking of the burner. Sludge formed of non-combustible materials that may be in the 7 fuel is collected in a chamber provided for that purpose. These materials may readily be removed by blowing down the burner while it is in operation througho iening of valve 4| momentarily and byusing this valve to draw fuel out of the burner for starting. Should the burner become clogged, the sludge-like material with which it is clogged can be readily removed by dissolving the same in fuel or by scraping it out of the chamber adjacent the nozzle, it having been found that this is the point'at which all of the sludge collects. Through the return of excess vapor into the fuel stream, temperature in the vaporizin unit is maintained and in addition, certain non-condensible gases in the vapor find their way into the supply tank so that the pressure in this tank is maintained automatically and as a consequence, the operating pressure of the burner is maintained more uniform.

Since the vaporizing unit, usually formed of pipe coiled as shown in the drawings, is maintained at a temperature below 750 F.',, ordinary iron pipe may be used with perfect safety, there by eliminating the use of the more expensive ialloy tubings nowrequired in burners of this While I have-chosen to show my invention by illustrating and describing a preferred embodiment of it, I have done so by way of exstances where secondary air of combustion is to have protected by Letters Patent ispointed out in the appended claims.

What is claimed is:

1. The method of burning liquid fuels which 1 comprises: subjecting the fuel to a working vaporizing unit and conduits of the humeral i he remainder of the vapor formed to the fuel to pre heat and agitate the fuel, heating air to a temperature substantially equal to the gasiflcationtemperature of said liberated vapor, mixing said liberated vapor with said heated ,air to gasify-the vapor, and passing the gas and air mixture so formed through a zone of primary combustion into a zone of secondary combustion in which zones the gas is burned.

2.'.The method of burning liquid fuelswhich comprises, building up a working pressure of approximately 35 pounds on the fuel, heating the. fuel under said pressure to a temperature below the cokingtemperature and above the vaporization temperature ofthe fuel at said pressure, liberating aportion of the vapor so formed from said -pressure, returning the remainder of the above the gasification temperature. ofsald' liber ated vapor,-mixing said heated airand-zth mainder of said liberated vapor and passing the g- "5. The method of burning liquid fuels which comprises: building up a working pressure of vapor so formed to said fuel under said pressure to pre-heat and agitate the fuel, heating air to a temperature substantially equal. to the gasi-. flcation temperature of a said liberated vapor, mixing said liberated vapor with said heated air to gasify the vapor, and passing the gas and air mixture so formed through a zone of primary combustion into a zone of secondary combustion in which zones the gas is burned.

comprises: building up! workingpressure of approximately 35 pounds on the fuel, passing a stream '01 said fuel under said pressure at a uniform rate through a zone that is maintained at a temperature below the coking temperature of the fuel and above the vaporization temperaand above the: vaporization temperature of the fuel at said pressure-to vaporize the fuel, lib-.

crating a portion of the vapor soformed' from 3. The method of burning liquid fuels which ture of the fuel at said pressure to vaporize the fueLliberatlng a portion of the vapor so formed from said pressure, returning the remainder of the vapor so formed to said fuel stream to preheat and agitate the fuel, heating air to a tam perature substantially equal to the gasification temperature 'ofsaid liberated vapor, mixing said liberated vapor with a sufl'icient quantity of said.

heated air to. gasify the vapor, and passing the gas and air mixture so formed through a zone of primary combustion into a 'zone of secondary combustion in which zones the gas is burned.

4; The method of burning liquid fuels which comprises: building up a working pressure .of approximately 35 pounds on the fuel, forming a stream of said fuel under pressure and passing said stream through a zone that is maintained at a temperature below the coking temperature and above the vaporization temperature of the fuel atsald pressure to "vaporize the fuel, liberat- 4 perature and above the vaporizing temperature j inga portion of the vapor so formed from said approximately 35 pounds on the'fuel, forming a streamof said fuel under pressure and passing said stream through a zone that is'maint'ained' ata temperature. below the coking temperature said pressure, returning the remainder of the vapor so formed to saidfuel stream to preheatand agitate the fuel, heating air to a tem-v peratur'e substantially equal to the gasiflcation temperature of the liberated vapor, mixing said. heated air-and said liberatedvapor Ito gasifythe vapor; burning a -pjartof.tl'ieggasso formed-m1 the presence of excess airitofiprovide heatfor:

the vaporizationof the fuel andfthejheating v.of.

the air,- and passing -the'remainder of the gas and air mixture through a zone of primary combustioninto a zone'of secondary combustion'in,

which zones the gas is burned.

6. The method of burning liquid fuels which."

comprises,.'building .up aworking pressure of approximately pounds on the fuel, heating said fuel to a, temperature below the coking temof the fuel at that pre'ssure to vaporize'the fuel,

liberating. from said pressure a portion 'of, the

vapor sofformed, returning the remainder of the vapor Jsoformedtosaidfuel under pressure to pre-heat and agitate the fuel, heating air to a temperature substantially equal-to the gasiflca tion temperature of said liberated vapor, ex panding said liberated vapor and simultaneously mixing said vapor and heated air to gasify the vapor, and passing the gas and air mixture so.

formed through a zone of primary combustion I into a zone of secondary combustion in which zones the v gas is burned;

vapor ,ytoa; saS yatm a nu; airmixture so formed through a zone i -primary combustioninto a zone of secondary combustion in which zones the gas is burned. 

